Lanci became Acer's CEO in 2008, and the company overtook Dell as the world's second-largest computer vendor during the third quarter of 2009, mainly benefiting from netbooks. However Acer's fortunes sunk as netbook shipments dropped and tablet shipments gained momentum. Analysts said Lanci's resignation reflected a difference of opinion in how aggressively Acer should shift its focus from consumer PCs and pursue mobile devices.

Acer in the past has thwarted Lenovo's expansion plans in Europe. Acer's acquisition of Gateway in 2007 derailed Lenovo's plans to acquire European PC vendor Packard Bell, which was ultimately acquired by Acer.

Lenovo was the fifth-largest PC vendor in EMEA (Europe, Middle East and Africa) in the fourth quarter last year, while Acer was the second largest, according to IDC. But on a worldwide basis, Lenovo is the second-largest PC vendor, while Acer is the third largest.

Lenovo hopes Lanci's past experience will help expand shipments of products, especially in Western Europe. PC shipments in EMEA fell by 6.5 percent in the fourth quarter last year, according to IDC.

Lenovo did not immediately respond to requests for comment on Acer's suit against Lanci.

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